Di-para-xylylguanidine



Patented Sept. 13, 1927.

' UNITED STATES PATENT OFFICE.

WINFIELD SCOTT, OF WILMINGTON, DELAWARE, ASSIGNOB TO E. I. DU PONT DENEMOUBS & COMPANY, OF WILMINGTON, DELAWARE, A CORPORATION OF DELA- WARE.

DI-PARA-XYLYLGUANIDINE.

No Drawing.

I \CHI To produce the new substance, either ammonia or ammoniumhydroxide may be caused to react with di-p-xylylthiourea in the presenceof a basic lead compound such as litharge. The di-p-xylylthiourea may beprepared for example by reaction be: tween carbon bisulphide andpara-xyhdine.

The production of dl-p-xylylguanldme may be illustrated by the followingexample:

Twenty-five (25) parts (by weight) of di-p-xylylthiourea (powdered) .isadded to one hundred and twelve '(112) parts by. weight of alcohol (95%alcohol containmg 0.5% benzol) at a temperature between about 40 and C.in a closed vessel. T0 the resulting mixture there is added slowly, withstirring, the thin paste formed from forty parts of litharge and 54parts of ordinary concentrated (28%) ammonlum hydroxide solution. Afterthe addition of the paste. is completed the reaction mass is kept at,atemperature of about 50 C. for about two hours with continuous stirring.

At the end of the two-hour heating period a sample is drawn off andfiltered'andthe filtrate warmed with some, fresh litharg'e. Ifdarkeningoccurs, anadditional amount, say -;'1020%v of litharge is added to theoriginal mixture and stirring continued for half amhour longer,whereupon the contents of the vessel are heated-to boilin and filteredhot by suction. The sludge Application filed November 27, 1922. SerialNo. 803,671.

is then extracted with the mother liquor I obtained aftercrystallizingthe first filtrate. A second extraction yields only a very small amountof the .dixylyl-guanidlne. After crystallization, the alcohol isdistilled off from the mother liquor; the residue extracted with dilutehydrochloric acid, preferably at room temperature, and an tarry materialinsoluble in the dilute aci is removed. The solution ofdi-p-xylylguanidine hydrochloride is then neutralized with caustic untilalkaline with Clayton'yellow to precipitate the base, which is thenfiltered and washed free from sodium chloride. The total yield is -82%of theoretical.

Since this imidation reaction is exothermic and will proceed at roomtempera ture it isnot necessary nor desirable to attain temperatures of607 0 C. A maximum temperature of 50 C. is all that is necessary andside reactions are greatly reduced. Avoiding a temperature above 50 C.is also desirable in the manufacture of diphenyland ditolyl-guanidinefrom the corresponding thioureas.

The newbase, di-para-xylylguanidine, has a melting point range. of fromto '170.5

C. The new compound is quite similar to diphenylguanidine anddi-o-tolylguani dine in its hysical and some of its chemical properties.It crystallizes from alcohol or toluene in needles. Thehydrochloride ofdi -p-xylylguanidine is quite soluble in cold water and' afiords aconvenient method of separating it from resinous products which maybeproduced during the amidation.

The chief utility, at present, of di-pxylylguanidine is in connectionwith the vulcanization of rubber for which it is an excellentaccelerator.

claim: l l i-para-xy y guam me. In testimony whereof I aflix mysignature.

- soo'r'r.

